Clutch-brake mechanism



l 1952 K. M. FEIERTAG 12,248

CLUTCH-BRAKE MECHANISM Filed June 2, 1950 IIJ/ I Inventor: Karl M. Fejertag,

His Attorney.

Patented Sept. 30, 1952 F- i vfie lee-i eeei eete sme r-A e r re ea t Myinvention relates to clutchand brake mech established between the twosuriaceatherhage M net-1c particles bind'the two elements together against movement parallel to their surfaces. The magnetic particles'may be finelydivided iron,

an preferably these particles are mixed l-withoil to prevent packing and to affords; SmOOthGI QOD- eration of the clutch and -'brake.. When. this iron-oil mixture is placed under the influence vof a magnetic field, the particles. are m'utually v at:- tracte'd; and the mixture seeminglyihardensfl or increases in viscosity to variable densities. pro:-

portional to the'app'lied field. .Since the amount of }=coupling oi? the twoelements. is determined by the densitybi the mixture, the .Icoupling may be -varied byvarying the-strength .0; l the, ma

missile?! insea e aaiz Q az 1-5i nd: the I ee ures of; neve yiw llib i99 i c aims annexed netic fleld. 'Sincebnly .a smalllamount of ,elec: v trical energy will effect magnetic saturation pf the-iron-oil mixture, la small electromagnetic 110-. tential :is adequate to obtain maximum coupling. An-ebie t -oi: -my=:invention :is to. provide an improved magnetic clutch: andzbizakmmeslhanism ime J agneticvfluid fily I Another-object er myinvention is .to provide andmproved-clutch and brake mechanism oi" the magnetic fluid type wherein .a magnetic-field ;as.-; sociated with the I brake: member. causes the mag: neticfluid to couple .a drivenmember tothe brake member, and .a magnetic field flfiqciated with the driving member causesjhe magnetic fiuid to couple..:the. driving :and driven members together. v i furtherobiect oi mydnvention is to provide a combined clutch :and brake mechanism of the magnetic fluid type in which a time delay, cc; eurs duringiwhich thetransier of the couplin oi-the driven member from one oithe control,- lingimembers :to the-other takesplace,

A still, further objec or mvi ve it pl i t pro: azideia combined clutch and brake mechanismpoi .thecmagnetic fluid type wherein the controlled men s-m vable to assume a P s ion loser to the ef ect ve cent m e e m n n .t be

mixture iEurtherlobiects-aand advanta es of my vinven- :tiQn-vwill become appar nt an y. i vention will ihehetterlu der eodf m t l ixiedeserip- QQ ?9 by ma eti a l u ceptible $1931 ireierrine to the accompanying "drawing :1

. producing a higherfluxfl oncentret e iiethe-ea 2:5

with particularity inc-t forming part of this specification nthe drawin E e-,.,.1- isas q a combined clutchi andbrake 'me ch nism qf t e1 ma etic fluid type. wh ch isi rovi. v,littit ei embodiment of-mm intention; Fi 2 is a; free -t n y sectiona r t ew show n o of the iron-oil mixture-when the r s coup ed heor ri mentary .sectionakvievw, t inv tionshowins--. an. a member.. s I p a A f of inventieniis the-me is ee mas etiefield e osedflthr ueheilie iivert el. oizthe-tmechanism in ongzvdtirect at thg-Q driven em s ermally eeuple o etbre e. member by m ansnof .taima etieal ysu ee ihle=i mi u e i the. sen be we nl liese mel her ka A" coil which is associated with the d iving-rnemb if; of. the mechanism creates merehle qr a. stmneer- Y a ne field closed through -,tne-- ri en memb in the; oppos t direction. ta tle irst-men w ed 11 1d betwee the drivin mem er; anQ.th :Q. 3 Y .1:.-.. ber and causing the magnetically; susceptible; mixture to concentrate-inth second-mer t ned gap and also acting on the mixture; ticeans mi ture too p e; he. drivlneiead the. e be st ee re A. second. feet ltef iihe vision of holes through the driven in rnberan a clearance between the ydriven memb nd housing of predetermined; t ta l; cros sectip area to regulate the speed at whichzt e ag}; netically susceptible-mixture may trans from one side of thelvdriven member; tqthefotlier o;

thereby provide. a; time d ybetween he- 0.4 pling of'the driven member'to the-brake- -mem ber and the couplingof the; driven member to the driving member. A; modificationof ;my; in; ventionis shown in Eig,.4-3;wh. r,ein;the driven member is. drawn toward .thelcontrolling; mem; ber having-l the magnet; producing the-hie er magnetic flux and iscoupledithereto by-the n ag netically susceptible mixture.v g

' As illustrated in -Fig. .'.1, the combined clutch andbrake includes a housing I, preferably, 01 cylindrical cross section, made. i ofsuitable, 7 none. magnetic material andclosed atithe. ends-by; removable covers or caps Land 3,.helditheretoe bysuitable screws orflboltsd and 5 respectiyely.,-

Cover or cap 3 is made-of :a. suitableymagneticg material and is provided with a fiange ficlhaving holes 1 through which bolts-or screws-may: bepassed to attach the combined clutch :and. brake.

axially magnetized. Obviously, permanent mag-, net I 3 could be replaced by a direct current excited coil over a magnetizable; core. l?ermanent magnet I 3 is ordinarily in the form of an annular ring concentric with driven shaftft',

Surrounding permanent magnet 13 is a non magnetic ring [4 which in turn is encased in :member' I5 which is L-shaped'iin crosssection '1, lMember I5 is made of a magnetic material and 1.,

provides a portion of magnetic flux path for'the imagnetic field of permanent magnet 13. The :fiux path for'the magnetic field off-permanent concentrated in gap It by drawing it through holes 21 and driven rotor 9 and around the perip-hery of rotor 9. After a time delay as described above shaft 8 resumes a normal brakeon condition.

In the modification of my invention shown in Fig. 3, in which like elements are shown by like reference numerals, rotor 9'is1f1xed .to shaft 8 by means of a spline or key wayso as to be axially movable. Shoulders 29 and 30 at the end "of spine 28 limit this movement. Normally, rotor 9 is drawn toward permanent magnet l3 and is coupled to brake member I2 by the magnetically susceptible mixture)! in gap I6. Coil 23 is of a magnet 13 isclosed through driven rotorSj-a's bestillustrated in Fig.1.

a v li ned with shaft 8 is the flfivm shaft l'l which may be connected to' anysource of power (not shown). Shaft IT extends through-' aperture I8 incover 3 and carries a rigidly se cured cup-shaped member [9 on its end adjacent the drivenr'otorii. 7 Cup-shaped rotor i9" coinpri'ses' a magnetic ri-ng ZOVsurr unding shaft l1, a spacer ring-2l made of a non-magnetic material; and an'outer ring 22 of a magnetic material. An energizable magnetizing winding 23, which is annular-in"form,is firmly'secured to coverii and. is provided by leads2'4 which are connected to the electrical supply source (not shown) A flux path for the magnetic field of winding 23 ispro-- vided'by end cover 3,-inner ring 29 of driving" rotor l9, driven--rotor 9,"and outer ring '22 of driving rotor i9, as bestillustrated in Fig. 2..

Likewise as illustrated in'Fig.-2, themagnetici field of winding 23' isstronger than that :pro-

duced byperm'anent m'agnet l3 Flux through. driven rotor 9 produced-by winding 23 is in op-1 positiontoflux through driven rotor 9 produced by permanent magnet I3. s

The cavity within housing I contains amag netically susceptible mixture 25. While any magnetically susceptible mixture could, be" used, I prefer to usethe mixture of powdered iron'and. oil. A grease seal '3l-whi'ch'is seated in an air-- nular recess of housing I surrounding' cup-'- shaped rotor I9 is provided to prevent the leakage of this mixture.

'Ino'peration, whencoil 23 is not energized; there is no coupling 'fiectbet'ween rotor i9 and;- driven rotor 9. Under these conditions, the magnetic field created by permanent magnet l3.is' closed through driven rotor 9' causing the magnetically susceptible mixture25 'to arrange'itselfT size to produce a magnetic field in cup-shaped rotor I9 of sufficient strength to draw driven motor 9, toward cup-shaped member 19 when coil 123 is energized, in opposition to the pull of pernanent'magnet [3. Thus when coil 23 is energized, driven rotor 9 is drawn toward cup-shaped rotorls'and is coupled theretoby the iron-oil mixture in gap 7'. g While this combined clutch and brake mocha-:

nism is intended primarily for- ,use with direct;

current, satisfactory alternating current ,-operation; especially; in the higher frequencies, could be obtained by making the magnetic portionof the driving assemblyof laminated material yi While I have illustrated and described particu-: lar embodiments'of my invention, modifications thereof will occur-to those skilled in the art. {1- wish it to be understood, therefore, that my in; vention is ,not limited; to particular arrangements disclosed, and I intend the :appended claims cover all modifications which do not depart from the spirit and scope ,of my;invention. M:

' What I claim as new and desire tosecu're by Letters Patent of the United, States, is: I A c0mbinedimagneticclutch and-brakeiin cludingra'magnetizable driven rotor havingoppo' sitely disposed sides, holesgthrough Saidrotor connecting said oppositely-disposed sides, ;a brake adjacent one side of said driven rotor and form ing a first gap therewith, a driving rotor adja; cent the opposite side .of said .dIlYBIl'IOtOIjQfi-Ildforming a second gap therewith;--said gaps con- -v taining a magnetically susceptible mixture a permanent magnet for said'kbrakeVcreating'apiag:

in gap 16', as'shown in Fig, 1 and to couple the.-

driven rotor 9 to thebrake member i2.

7 As soon'as coil 23 is energized, a strongerniag netic flux concentration is created'in'gap'la than. exists in gap 16. However,.since most of the iron. powder is concentrated'in gap-idia timedelay occurs until sufiicient powder is drawn around,

netic field in said first :igap-to concentrate said mixture in saidtfirst gap and ;to cause saidmixture to couple said dri'venrrotor jtO -S3iid-bIakQ, and an energizable magnetizing Winding; for; said driven member capable of creatingamagnetic field in said secondgap of greater strength than said first-mentioned magnetic field,said seconde mentioned magnetic field drawing said" mix-ture through the holes in'said driven, rotor thereby causing said mixture to concentrate in said'see g- 0nd gap and then to couple said driving and said driven rotors together when saidcoilris'eners n 2. A combinedmagnetic fluid clutchtand' brake comprising a non-magnetizable-housin g journaling a shaft carrying a driven rotor havingoppo sitely disposed sides, a pluralityof holesin said driven rotor connecting said sides}: said driver-1 rotor and said housing "defining a peripheral clearance therebetween, a brake adjacent one side of said driven rotor and forming a first ga'p therewith, a driving rotor adjacent the opposite side of said driven rotor and forming afseqqnd gap therewith, said gaps containing' aniro'n-oil mixture, magnet means forsaid brake -'creating a magnetic field in said first 'gap to concentrate said mixture in said first gap and' to'cause said mixture to couple said driven rotor to said brake. and coil means for said driving member capable of creating a'magnetic field in said second gap of greater strength than said first-mentioned magnetic field, said'second-mentioned magnetic field drawing said mixture through the holes in said driven rotor and around the peripheral clearance of said driven rotor causing said mixture to concentrate in said second gap and after a time delay to couple said driving and driven rotors together whensaid coil is energized. 3. A combined magnetic fluid clutch and brak comprising a non-magnetizable housing journaling a shaft carrying a driven rotor having oppositely disposed sides, said driven rotor and said housing defining a peripheral clearance therebetween, said peripheral clearance having'a predetermined cross sectional area, a brake adjacent one side of said driven rotor and forming a first gap therewith, a driving rotor adjacent the opposite side of said driven rotor and forming a second gap therewith, said gaps containing an iron-oil mixture, magnet means for said brake creating a magnetic field in said first gap to concentrate said mixture in said first gap and to cause said mixture to couple said driven rotor to said brake, and coil means for said driving member capable of creating a magnetic field in said second gap of greater strength than said first-mentioned magnetic field, said second-mentioned magnetic field drawing said mixture around the peripheral clearance of said driven rotor causing said mixture to concentrate in said second gap and after a time delay to couple said driving and driven rotors together when said coil is energized.

KARL M. FEIERTAG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Bureau of Standards Technical Report 1213 of March 1948. 

